JGS524PE not working with Reolink RLC-823A

Almost  classic one. However, you complain on the wrong end of the data and PoE chain.

According to https://reolink.com/product/rlc-823a/#specifications 

Power
PoE IEEE 802.3at, 48V Active

DC Power DC 12.0V⎓2A, <24W

According to the datasheet (and the marketing information), the JGS524PE does have 802.3af PoE capability, so able to supply max 12.95 W on the PoE devices (PD), on the power source equipment (PSE) side, direct on the switch port and before the cable, this is 15.4W.

IEEE 802.3at also known as PoE+ is able to to supply max 25.5 W on the PoE devices (PD), on the power source equipment (PSE) side, direct on the switch port and before the cable, this is 30W. 

Key issues are not ideal marketing (Reolink should add PoE+) paired poor (low cost) hardware engineering. This camera like this RLC-823A requiring 802.3at (PoE+) must not boot if the PSE does indicate it's 802.3af (PoE) only, instead is should indicate a power source issue instead. The "48V Active" add-on information is not required (it's part of the standard), but it might avoid customers complain certain passive PoE devices can't power the camera. And of course, the information I'm providing here must be part of the Reolink documentation.

Of course you don't want to update a working PoE switch, so consider to add an IEEE 802.3at PoE+ power injector. Due to the handshake, there is no risk to operate this on a standards compliant IEEE 802.3af PoE switch port.